need suggestions for term

A fantasy story takes place in an alternative reality with slightly different physical laws, whereby atomic particles like protons, neutrons, etc. are found to have a different internal structure than in our reality, reminiscent of the structure of living cells. (For non-physicists: protons and neutrons are made of quarks in the real universe.) In this reality, one of the new components in a proton is analogous to a nucleolus in a living cell. Should I call it a nucleolus, or should I think of another word (not coined) that is similar? Not "nucleus" or "core": these words are already taken. Any suggestions?